Many of the designators on the list are out-of-date and no longer in service. I have updated the list with current designators:
1-22: District Cars (except 3, 4, 10)
25: ISP TRT Cars
A: ISP Division of Administration
#AG#: Attorney General Investigators
B: ISP District Fleet Officers
C: ISP District Chicago Cars
DA: IL State Fire Marshal Arson Investigators
E: ISP Executive Protection Unit
F#: ISP Division of Forensic Services (Crime Scene Services)
#F#: IL DNR Conservation Police
FA: DNR/Conservation Administrative Units
FW: US Fish and Wildlife Agents
H: ISP Academy Personnel
H###: IDOT Portable Scale Operators
IC: IL Commerce Commission Police
#I# Zone (#) Investigations Special Agent - 7I2 (Zone 7 Lieutenant)
#J#: IL Secretary of State Police Department
K: IL Department of Corrections
L: ISP Pilots on the Ground
M: ISP Motorcycle Units
N: ISP Division of Internal Investigations
O: ISP Division of Operations
P: ISP Air Operations Planes in Flight
PS: ISP Protective Security - Thompson Building (Chicago)
R: ISP Riverboat Gambling Unit
xR: ISP District Telecommunication Personnel
S: ISP District Safety Education Officers
SC: ISP Fixed Weigh Station
T: ISP Radio Lab Staff
V: ISP District Vehicle Investigations Officer
X: ISP District 10 Units
Y: IL Department of Revenue Investigators
Z/Car: ISP Director's Office (Car One is Director, Entered into Computer Z01)
The Ocean cars are a catch-all; they can be anything from O-10, the southern Investigations Major, to O-54, a sergeant over crash investigations, to O-155, a Medicaid fraud investigator, to O-181, a trooper in crash reconstruction.
The roving O-200 series is the statewide criminal interdiction team.